CVE-2003-1013 in Ethereal
Summary
by MITRE
The Q.931 dissector in Ethereal before 0.10.0, and Tethereal, allows remote attackers to cause a denial of service (crash) via a malformed Q.931, which triggers a null dereference.
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Analysis
by VulDB Data Team • 09/05/2019
The vulnerability identified as CVE-2003-1013 represents a critical denial of service flaw affecting the Q.931 dissector implementation in network protocol analysis tools. This issue impacts both Ethereal versions prior to 0.10.0 and its successor Tethereal, which were widely used network traffic analysis platforms for capturing and inspecting network packets. The Q.931 protocol is part of the ISDN (Integrated Services Digital Network) standard and is used for call control signaling in telecommunications networks. The dissector component within these tools is responsible for parsing and displaying Q.931 protocol data within captured network traffic, enabling network administrators and security professionals to analyze telecommunications signaling information. The flaw occurs when the dissector encounters malformed Q.931 packets that do not conform to expected protocol structures, specifically those containing invalid or unexpected data patterns that cause the analysis tool to crash.
The technical root cause of this vulnerability stems from insufficient input validation within the Q.931 dissector implementation, classified under CWE-476 as a NULL pointer dereference vulnerability. When the dissector processes malformed Q.931 packets, it attempts to access memory locations that have not been properly initialized or validated, leading to a null pointer dereference condition. This type of error typically occurs when the software assumes that a pointer variable contains a valid memory address, but in reality, the pointer is null or uninitialized. The vulnerability manifests as an application crash when the dissector attempts to parse fields within the malformed Q.931 packet structure, particularly when handling unexpected packet lengths, missing headers, or corrupted data fields. The crash occurs during the packet parsing phase, effectively rendering the network analysis tool unusable until it is restarted, creating a denial of service condition that prevents legitimate network analysis activities.
From an operational perspective, this vulnerability presents significant risks to network security monitoring and incident response activities. Network administrators who rely on Ethereal or Tethereal for network traffic analysis and troubleshooting could experience complete service disruption when encountering malicious or malformed Q.931 traffic in their network captures. The remote attack vector means that an attacker could potentially send specially crafted Q.931 packets to a system running these tools, causing it to crash and interrupt ongoing network monitoring operations. This vulnerability impacts the availability of network analysis capabilities and could be exploited to disrupt network security operations, particularly in environments where continuous monitoring is critical for detecting security incidents or network anomalies. The attack requires minimal technical expertise to execute, as it only requires sending malformed Q.931 packets to a system running the vulnerable software, making it an attractive vector for attackers seeking to disrupt network monitoring activities.
The remediation for this vulnerability involves upgrading to Ethereal version 0.10.0 or later, where the Q.931 dissector has been patched to properly validate input data and handle malformed packets gracefully without causing application crashes. The fix implemented in the patched versions typically includes enhanced input validation routines that check for null pointers before dereferencing them, proper bounds checking for packet data structures, and robust error handling mechanisms that prevent the application from crashing when encountering malformed data. Organizations should also implement network segmentation and access controls to limit exposure to potentially malicious traffic, while maintaining updated network monitoring tools to ensure continued operational capability. From a defensive standpoint, this vulnerability highlights the importance of input validation and error handling in network security tools, as demonstrated by the ATT&CK framework's emphasis on defensive techniques related to input validation and software reliability. The vulnerability serves as a reminder of the critical need for proper software testing and validation of protocol parsers, particularly in security tools where reliability and availability are paramount for effective network monitoring and threat detection operations.